Do you know the nature and purpose of the different chemical solutions ? If not, you should, for this is the key to success in handling the solutions properly to produce the desired effects.

Take D. O. P. developers for instance, and you will find that as a rule they are made of from three to five different chemicals, each chemical having a distinct and different function.

True, you are given printed formulae for mixing the various baths you need to complete your pictures and the chemical packages are all labeled, and if you follow these formulae carefully and are sure you use the proper chemical in each instance, there doesn't seem to be much of a chance to go wrong and there isn't: but supposing some one of the chemicals isn't quite as active as it should be, due to local water conditions, etc., and the prints are not all that you wish, would you be able to tell from the appearance of the prints what was wrong ?

Supposing the fixing bath turned milky instead of remaining clear, or supposing your developer turned black either before use or shortly after being in use, would you know the cause and how to prevent a recurrence in the future?

Do you know enough of the nature of the chemicals you to use them intelligently to produce the effects you want? You should be able to control the tone and quality of prints to exactly meet your requirements, and you will be able to do it if you become familiar with chemical action.

You need not necessarily take a course in chemistry to learn what you need to know, and there is a book on D. O. P. manipulation published especially for you which will help you to know many of the things you ought to know in connection with the use of the best developing paper ever produced - Artura.

The ninth edition of Artura Results, which you may procure from your dealer or from us by mail, treats upon these things and will put you on speaking terms with the whys and wherefores of your chemical combinations and help you to secure results that are exactly what you want.

Artura is a high grade professional portrait paper and Artura Results will enable the intelligent worker to bring out that high grade quality to the fullest extent.

If you haven't a copy of the ninth edition of Artura Results send for it to-day. It is free to all professional photographers for the asking and has helped many in producing prints of highest quality.